My little sister was also born in 1990, she was born exactly one month before you. She has this similar stellium, except in her 1st house, with Saturn, Venus, Mercury, Mars, Neptune, Uranus, and Venus, all lined up with an opposing Jupiter in cancer, very similar to yours. She takes life very seriously, is entrepreneurial, career-oriented, with an assertive personality. She has no problem speaking up for herself or others. Lots of integrity, but has a pluto-conjunct-moon, so she can be moody in dealing with her powerful emotions, and will isolate herself from others from time to time to deal with it.
Stelliums make the planets associated with it work as a functioning unit, rather than separately.
This sort of stellium has effected the birth charts of a generation. I think it's promising to say that the birth group you all rode in on has a very Capricorn approach in dealing with the world- hard working (!), goal-oriented with a certain level of dedication, ambitious, determined, and smart enough to know that life won't be handed to you. It's wonderful, really, but also very intense and difficult. There is of course, a downside to Capricorn. It can be miserly, frugal, cold, calculatingm materialistic, greedy...
You are much more Capricorn like than most anything.
Aside form your stellium, you possess personal MAGNETISM with your sun so closely conjunct your ascendant. It's a very powerful position for the sun, even for a Pisces. It's funny, you have in common my sister's stellium and opposing jupiter, and my own Pisces sun and ascendant with Mercury in Aquarius in the 12th.